The invention relates to heat treatment for metal articles in a roll type furnace, in particular for relatively thin steel parts which easily warp when exposed to heat, such as ball bearing raceways, sheet metal rounds, blades and the like.
A device for heat treatment for metal articles is known (DE-PS 31 50 576), in which annealing frames equipped with the metal parts in the single divisions are disposed upon a rolling track. The annealing frames equipped with the metal articles are run through a furnace. It is however difficult to prevent that metal parts with a lengthwise dimension of some centimeters and a small thickness of some millimeters are not warped permanently after the heat treatment.
Furthermore, in connection with the heat treatment of metal parts it is up to now usual to use furnaces comprising an atmosphere containing protective gas and with partially electrical heating in order to prevent that e.g. the carbon content of the metal parts changes during the heat treatment process or the metal parts oxidize. For most metal parts, neither recarburization nor decarburization nor oxidation is desired.